Dinosaur AI rework

I was stood on a hill watching the dinosaurs in the distance. Nearly every time I looked, they were on the move. It looked a bit like a crowd milling about at a concert.

Part of that came from how I'd set up migration. The game keeps track of a dinosaur even when it's too far away to see. I wanted animals to move through the parts of the map that suit them, so that a herd I'd seen earlier might have moved on by the time I came back. I'd set things up so that they looked like they were always on their way somewhere.

While I was looking at that, I started testing how much work the dinosaurs give the server. I'd like to support up to 32 players on a server. The game loads a few hundred metres of terrain around each player, along with the animals that live there. If everybody spreads out, the server has to keep all those separate areas running at once. I've been using bots to measure what that costs.

The old population settings also left the world feeling a bit empty. I've raised the target population for many of the herd species and pack hunters to four times what it was. That sounds like a lot until you remember how few there were to begin with.

Herds now spend more time in one place before moving to another part of their home range. I used to watch a herd of Gallimimus and see them all do the same thing at once. Now one can stop to eat while another carries on walking, and they still move together as a herd. I've added some variation to the resting and feeding poses too. Those poses are defined in data, which is something I'd like modders to be able to use later.

I've also changed how they turn. Early on I made them walk through every turn. I liked the way a big dinosaur like a T-Rex swung round in a wide arc, right up until it walked into a tree and got stuck. I let them turn on the spot after that, and I think I took it too far. Now they'll turn in an arc if there's room and turn on the spot if they're boxed in.

It feels better in the testing I've done so far. I expect I'll keep coming back to it as I spend more time watching them.